Black Panther is TChalla, the prince of Wakanda, and being the Panther isnt some sort of secret identity he assumes at night. The monarchs of Wakanda defend their people as the Black Panther, a traditional warrior role. Its a mantle that has been passed down for generations. TChalla, played by Chadwick Boseman, will be in the Panther suit in Civil War, but does he begin the movie as the Black Panther? I asked Kevin Feige about this at the Ant-Man junket.
I dont know how to answer that question without spoiling it! Feige said. It is a role that he is still in the beginning phases of taking on, its a mantle he is only beginning to take on because his father is older.
So as TChaka, his father, prepares to hang it all up prince TChalla prepares to take on the mantle. We can assume that at some point in the film it is passed down - whether that be after TChaka retires or after he dies remains to be seen. io9 today reported that a future Marvel film could be an origin story set in the past, but this information makes it clear that movie will not be Black Panther.
So if this is going to be a movie where TChalla takes on the Black Panther mantle why introduce him now? Why not wait for a solo film? Said Feige:
The reason we introduced him in Civil War is because we needed a third party. We needed fresh eyes who wasnt embedded with the Avengers and who has a very different point of view than either Tony or Steve. We said, We need somebody like Black Panther
why dont we just use Black Panther? Thats how it went in the development process.